Polymer removal from top surfaces and sidewalls of a semiconductor wafer

Abstract

A process for producing a strip removes photoresist and extraneous deposits of polymer residue on the top surface and sidewalls of a post-metal etch wafer. The photoresist and residue are processed simultaneously by a chemical mechanism comprising reactive species derived from a microwave-excited fluorine-containing downstream gas, and a physical mechanism comprising ion bombardment that results from a radio frequency excited plasma and accompanying wafer self bias. A vacuum pump draws stripped photoresist and residues from the surface of the wafer and exhausts them from the chamber.

We claim: 
     
       1. In a process chamber, a process for stripping photoresist and polymer residues from top surfaces and side walls of a post-metal etch semiconductor wafer, comprising the steps of: initiating a flow of feed gas comprising fluorine-containing gases upstream from said process chamber;   applying to said feed gas means for producing a plasma;   supplying effluents of said plasma in the form of reactive species separated from said plasma to said process chamber;   applying radio frequency energy to said wafer in said process chamber to generate a lower intensity plasma therein and accompanying wafer self-biasing;   applying a magnetic field that rotates slowly in the horizontal plane to said process chamber during said step of applying radio frequency energy to said wafer to enhance plasma generation; and   stripping said photoresist and polymer residues from the top surfaces and side walls of said post metal-etch wafer with said reactive species and said lower intensity plasma wherein the pressure in said process chamber is greater than 100 miliTorr.     
     
     
       2. The process of claim 1, wherein said plasma producing means is either of microwave energy and radio frequency energy. 
     
     
       3. The process of claim 1, wherein said fluorine-containing gases are either of CF 4 , and SF 6 . 
     
     
       4. The process of claim 1, wherein said radio frequency energy is generated at a frequency of 13.56 MHz. 
     
     
       5. The process of claim 4, wherein said radio frequency energy is modulated. 
     
     
       6. The process of claim 1, further comprising the steps of: vaporizing water;   delivering said vaporized water into said feed gas at a controlled flow rate that is low enough to avoid saturation of said feed gas thereby; and   forming a passivation layer on said post-metal etch wafer.   
     
     
       7. The process of claim 1, further comprising the step of: drawing said photoresist and polymer residues away from said post-metal etch wafer and exhausting said photoresist and polymer residues from said process chamber with a vacuum pump.   
     
     
       8. A process for removing photoresist and polymer residues from a post-metal etch wafer in a process chamber, comprising the steps of: initiating a flow of feed gas comprising fluorine-containing species upstream from said process chamber;   vaporizing water;   delivering said vaporized water into said feed gas at a controlled flow rate that is low enough to avoid saturation of said feed gas thereby;   applying to said feed gas a means for producing a plasma, such that a reactive species is generated thereby;   supplying effluents of said plasma and separated from said plasma to said process chamber;   applying radio frequency energy to a wafer chuck in said process chamber to generate a lower intensity plasma with said reactive species and accompanying wafer self-biasing;   applying a magnetic field that rotates slowly in the horizontal plane to said process chamber;   stripping said photoresist and polymer residues from said post metal-etch wafer with said reactive species and lower intensity plasma;   drawing said photoresist and polymer residues away from said process chamber with a vacuum pump; and   forming a passivation layer on said post-metal etch wafer wherein the pressure in said process chamber is greater than 100 miliTorr.   
     
     
       9. The process of claim 8, wherein said radio frequency energy is generated at a frequency of 13.56 MHz. 
     
     
       10. The process of claim 8, wherein said radio frequency energy is modulated. 
     
     
       11. The process of claim 1, wherein said photoresist and polymer residues are isotropically stripped from said up top surface and side walls of said post metal-etch wafer. 
     
     
       12. The process of claim 8, wherein said photoresist and polymer residues are isotopically stripped from said up top surface and side walls of said post metal-etch wafer.